In the past, storage tanks for two different liquids have been constructed with a flat barrier wall or bulkhead to divide the interior of the tank into two separate compartments. This construction is usually satisfactory when the liquid volume in both compartments is the same. However, a problem occurs when the liquid levels are substantially different. For example, after liquid is withdrawn or partially withdrawn from one compartment but not the other, the liquid pressure on the two sides of the flat bulkhead will be unequal and as a result the bulkhead may bulge or become warped or distorted, sometimes causing a failure of the weld between the bulkhead and the tank wall. The problem of unequal pressures also is present when one compartment or the other is tested for leaks by the introduction of air under pressure.
One object of this invention is to provide a dual compartment storage tank which overcomes the problems associated with prior tanks of this type. In accordance with a specific embodiment to be described, the bulkhead is curved in an arc rather than flat and is therefore much more resistant to unequal pressures.
Another object is to provide a dual storage tank which is composed of a relatively few simple parts, is rugged and durable in use, and is easy to manufacture, maintain and assemble.
Other objects, features and advantages of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying drawings.